fix(desktop): raise Chromium WebGL context cap to 256 by Kitenite · Pull Request #3834 · superset-sh/superset

Kitenite · 2026-04-28T18:02:14Z

Chromium defaults max-active-webgl-contexts to 16 per renderer process. Each xterm holds one WebGL context, and the v2 parking model keeps panes alive across workspace switches, so cumulative panes routinely reach the low hundreds. Once over the cap, Blink forcibly fires webglcontextlost on the oldest pane, producing the blank/garbled terminals in #3572, #3504, #3527.

Raising to 256 covers low-hundreds of cumulative panes while staying bounded enough to surface a real leak. Does not address upstream xterm.js texture-atlas bugs (xtermjs/xterm.js#5849), which manifest as similar corruption but require a different fix.

Description

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Summary by cubic

Raise Chromium’s active WebGL context limit from 16 to 256 to stop terminals from blanking when many panes persist across workspace switches. Adds the max-active-webgl-contexts command-line switch so older contexts aren’t evicted under load.

^{Written for commit bc55d17. Summary will update on new commits. Review in cubic}

Summary by CodeRabbit

Chores
- Enhanced WebGL context handling to improve stability and performance when using terminal panes across multiple workspaces.

Chromium defaults `max-active-webgl-contexts` to 16 per renderer process. Each xterm holds one WebGL context, and the v2 parking model keeps panes alive across workspace switches, so cumulative panes routinely reach the low hundreds. Once over the cap, Blink forcibly fires `webglcontextlost` on the oldest pane, producing the blank/garbled terminals in #3572, #3504, #3527. Raising to 256 covers low-hundreds of cumulative panes while staying bounded enough to surface a real leak. Does not address upstream xterm.js texture-atlas bugs (xtermjs/xterm.js#5849), which manifest as similar corruption but require a different fix.

coderabbitai · 2026-04-28T18:02:33Z

No actionable comments were generated in the recent review. 🎉

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Reviewing files that changed from the base of the PR and between 89285e4 and bc55d17.

📒 Files selected for processing (1)

apps/desktop/src/lib/electron-app/factories/app/setup.ts

📝 Walkthrough

Walkthrough

A Chromium command-line switch max-active-webgl-contexts is configured with a value of 256 during Electron app initialization to increase the maximum number of retained WebGL contexts across workspace operations.

Changes

Cohort / File(s)	Summary
WebGL Context Configuration `apps/desktop/src/lib/electron-app/factories/app/setup.ts`	Added `max-active-webgl-contexts` Chromium command-line switch set to 256 to allow more concurrent WebGL contexts in terminal panes.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Poem

🐰 A whisker twitch, a config line,
WebGL contexts now align!
Two hundred fifty-six gleam bright,
Terminal panes shine with light!
GPU memory takes its flight! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: raising Chromium's WebGL context cap to 256, which directly corresponds to the code modification in the pull request.
Description check	✅ Passed	The description is mostly complete with detailed rationale and context about the issue, but the template sections (Related Issues, Type of Change, Testing) are not filled in beyond the template placeholders.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Commit unit tests in branch debug-webgl-terminal-v2

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Drop issue references (belong in PR description) and Chromium source path (rots if files move). Keep the WHY: parking holds contexts, default 16 is too low at hundreds of cumulative panes, 256 is bounded enough to surface leaks.

greptile-apps · 2026-04-28T18:03:20Z

Greptile Summary

This PR raises Chromium's max-active-webgl-contexts switch from the default 16 to 256 in the Electron app setup, fixing blank/garbled terminal panes caused by webglcontextlost events when the v2 parking model accumulates more than 16 live xterm WebGL contexts across workspace switches.

The fix is well-scoped and thoroughly documented. One minor observation: the switch is applied unconditionally on all platforms, including Linux where app.disableHardwareAcceleration() already disables WebGL — the switch is harmless there but has no effect.

Confidence Score: 5/5

Safe to merge — targeted one-liner fix with excellent rationale, no logic or security concerns.

The change is a single well-justified Chromium command-line switch addition. All findings are P2 or lower (Linux no-op is harmless). No data-integrity, security, or correctness issues are present.

No files require special attention.

Important Files Changed

Filename	Overview
apps/desktop/src/lib/electron-app/factories/app/setup.ts	Adds `max-active-webgl-contexts` Chromium switch set to 256, raising the cap from the default 16 to prevent forced `webglcontextlost` events on xterm panes; change is unconditional across all platforms including Linux where hardware acceleration is already disabled.

Sequence Diagram

sequenceDiagram
    participant App as Electron App (startup)
    participant Chromium as Chromium Renderer Process
    participant xterm as xterm.js pane (WebGL)

    App->>Chromium: appendSwitch("max-active-webgl-contexts", "256")
    note over Chromium: cap raised from 16 → 256

    loop Each new pane opened / workspace switch
        xterm->>Chromium: request WebGL context
        Chromium-->>xterm: context granted (v2 parking keeps alive)
    end

    note over Chromium,xterm: Before fix: >16 contexts → ForciblyLoseOldestContext → webglcontextlost → blank terminal
    note over Chromium,xterm: After fix: up to 256 contexts before eviction kicks in

_{Reviews (1): Last reviewed commit: "deslop: trim WebGL cap-raise comment" | Re-trigger Greptile}

cubic-dev-ai

No issues found across 1 file

cubic-dev-ai

No issues found across 1 file

github-actions · 2026-04-28T18:30:40Z

🧹 Preview Cleanup Complete

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⚠️ Neon database branch

Thank you for your contribution! 🎉

deslop: trim WebGL cap-raise comment

bc55d17

Drop issue references (belong in PR description) and Chromium source path (rots if files move). Keep the WHY: parking holds contexts, default 16 is too low at hundreds of cumulative panes, 256 is bounded enough to surface leaks.

cubic-dev-ai Bot reviewed Apr 28, 2026

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Kitenite merged commit a8e8556 into main Apr 28, 2026
7 checks passed

Kitenite deleted the debug-webgl-terminal-v2 branch April 28, 2026 18:30

SilkePilon mentioned this pull request Apr 28, 2026

chore: sync with upstream SilkePilon/superset#2

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MocA-Love mentioned this pull request May 8, 2026

upstream merge 2026-05-08 PR 1: v2 polish 前半 safe set MocA-Love/superset#455

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fix(desktop): raise Chromium WebGL context cap to 256#3834

fix(desktop): raise Chromium WebGL context cap to 256#3834
Kitenite merged 2 commits into
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debug-webgl-terminal-v2

Kitenite commented Apr 28, 2026 •

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Description

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Summary by cubic

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greptile-apps Bot commented Apr 28, 2026

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Confidence Score: 5/5

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Kitenite commented Apr 28, 2026 •

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